// Copyright (C) Kumo inc. and its affiliates.
// Author: Jeff.li lijippy@163.com
// All rights reserved.
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published
// by the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program.  If not, see <https://www.gnu.org/licenses/>.
//
#pragma once
#include <vector>

namespace kumo::pollux::common::hll {
    // These tables come from Presto's HLL implementation:
    // https://github.com/airlift/airlift/blob/master/stats/src/main/java/io/airlift/stats/cardinality/BiasCorrection.java
    //
    // These tables are generated empirically by running several thousand
    // experiments and computing the average error for each cardinality
    //
    // See HyperLogLog in Practice: Algorithmic Engineering of a State of The Art
    // Cardinality Estimation Algorithm paper at
    // https://stefanheule.com/papers/edbt13-hyperloglog.pdf
    class BiasCorrection {
    public:
        static const std::vector<std::vector<double> > kRawEstimates;
        static const std::vector<std::vector<double> > kBias;
    };
} // namespace kumo::pollux::common::hll
